At last, a movie that understands the surest way to sell an important message is to come in through the lowbrow door. The film is the slyly inflammatory mockumentary C.S.A.: Confederate States of America, and the door is marked "alternate history"  that pulp-drunk school of speculative fiction that stands a famous real-life occurrence on its head, pondering how the world might look today had destiny zigged instead of zagged. C.S.A. takes one of the most obvious alt-historical posers possible  "What if the South had won the Civil War?"  and uses it as the springboard for a deadpan satire that's as fun as it is smart. And as such, it might actually be seen.

The tale is told in the form of a TV documentary  British-made, a preamble informs us, and getting a rare stateside airing thanks to the open-mindedness of a (but of course!) San Francisco station. Via a familiar-looking pastiche of on-camera re-creations, archival footage, still art and talking-head interviews with modern-day historians, the doc "explains" how the Confederacy was able to conscript England and France into its cause by publicizing the war it was fighting as a battle for states' and property rights, pushing the messy concept of slavery to the background. With the balance of power tipped, the South took the White House and instituted the Confederate States of America, a new and proud nation dedicated to preserving the plantation way of life and advancing the manifest destiny of white supremacy throughout the Western Hemisphere.

The extrapolations are meticulously thought out. Writer-director Kevin Willmott, an assistant professor of theater and film at the University of Kentucky, amplifies historical precedent in a way that takes no prisoners and respects no sacred cows. Abraham Lincoln is pilloried as a racially insensitive pragmatist who paid dearly for his lack of commitment to abolitionism: Spirited away from a besieged White House by none other than Harriet Tubman, he's said to have been caught riding the underground railroad and brought to trial, his blackface disguise having failed to fool his Confederate captors. In contrast, Jefferson Davis is painted as a significantly more sympathetic figure, one who ultimately urged his countrymen to move away from slavery and decried from his deathbed the anti-Semitism his nation had likewise embraced.

We follow the development of that nation all the way into the present, learning how a culture steeped in overt racism comported itself geopolitically and in the home. Frequent commercial breaks  which hawk products predicated on all manner of offensive stereotypes  remind us that the C.S.A. hasn't exactly become enlightened over the course of 140 years. The stinging critique works because it dares to be funny, at one point winning the Blazing Saddles award for fearless comedy by christening a sports team the New York Niggers. Only once does the parody border on genuine poor taste, as the concept of a World War II battalion of fighting slaves risks insult to the real men of color who risked their lives on the battlefield.

The production values aren't what one would call consistent, with cheap-looking video footage and occasionally stiff line readings undermining the clever choices of scripted voice, onscreen text and background music. But the missteps never get in the way of the grand, bitter joke at the movie's center: Though the reality of C.S.A. differs from ours in countless cosmetic ways, on a more substantive level, everything is exactly the same. The result of every presidential election is unchanged (up to and including the Reagan era, at least). The TV airwaves are still filled with sitcoms that propagate shuffling, foolish caricatures of blackness. And the radicals of the 1960s still fight a losing battle for equal rights, which in this reality at least are called by their proper name of "freedom." Some imagination, huh, kids? Mere minutes after I had finished watching the movie, I glanced at a newspaper and came across this headline: "Group wants Confederate flag on tags." I had no idea which world I was living in, and that's exactly the point Willmott wanted to make. Game, set and match to C.S.A.. See it as soon as you can.